1 /* $OpenBSD: base64.c,v 1.3 1997/11/08 20:46:55 deraadt Exp $ */
2 /*
3 * Copyright (c) 1996 by Internet Software Consortium.
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
10 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
11 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
12 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
13 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
14 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
15 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
16 * SOFTWARE.
17 */
18
19 /*
20 * Portions Copyright (c) 1995 by International Business Machines, Inc.
21 *
22 * International Business Machines, Inc. (hereinafter called IBM) grants
23 * permission under its copyrights to use, copy, modify, and distribute this
24 * Software with or without fee, provided that the above copyright notice and
25 * all paragraphs of this notice appear in all copies, and that the name of IBM
26 * not be used in connection with the marketing of any product incorporating
27 * the Software or modifications thereof, without specific, written prior
28 * permission.
29 *
30 * To the extent it has a right to do so, IBM grants an immunity from suit
31 * under its patents, if any, for the use, sale or manufacture of products to
32 * the extent that such products are used for performing Domain Name System
33 * dynamic updates in TCP/IP networks by means of the Software. No immunity is
34 * granted for any product per se or for any other function of any product.
35 *
36 * THE SOFTWARE IS PROVIDED "AS IS", AND IBM DISCLAIMS ALL WARRANTIES,
37 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
38 * PARTICULAR PURPOSE. IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL,
39 * DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER ARISING
40 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE, EVEN
41 * IF IBM IS APPRISED OF THE POSSIBILITY OF SUCH DAMAGES.
42 */
43
44 #include "gpsd_config.h" /* must be before all includes */
45
46 #include <stdlib.h>
47 #include <sys/types.h>
48 #include <ctype.h>
49 #include <stdio.h>
50 #include <stdlib.h>
51 #include <string.h>
52 #include <assert.h>
53
54 #include "gpsd.h" /* we only need the prototype */
55
56 static const char Base64[] =
57 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
58 static const char Pad64 = '=';
59
60 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
61 The following encoding technique is taken from RFC 1521 by Borenstein
62 and Freed. It is reproduced here in a slightly edited form for
63 convenience.
64
65 A 65-character subset of US-ASCII is used, enabling 6 bits to be
66 represented per printable character. (The extra 65th character, "=",
67 is used to signify a special processing function.)
68
69 The encoding process represents 24-bit groups of input bits as output
70 strings of 4 encoded characters. Proceeding from left to right, a
71 24-bit input group is formed by concatenating 3 8-bit input groups.
72 These 24 bits are then treated as 4 concatenated 6-bit groups, each
73 of which is translated into a single digit in the base64 alphabet.
74
75 Each 6-bit group is used as an index into an array of 64 printable
76 characters. The character referenced by the index is placed in the
77 output string.
78
79 Table 1: The Base64 Alphabet
80
81 Value Encoding Value Encoding Value Encoding Value Encoding
82 0 A 17 R 34 i 51 z
83 1 B 18 S 35 j 52 0
84 2 C 19 T 36 k 53 1
85 3 D 20 U 37 l 54 2
86 4 E 21 V 38 m 55 3
87 5 F 22 W 39 n 56 4
88 6 G 23 X 40 o 57 5
89 7 H 24 Y 41 p 58 6
90 8 I 25 Z 42 q 59 7
91 9 J 26 a 43 r 60 8
92 10 K 27 b 44 s 61 9
93 11 L 28 c 45 t 62 +
94 12 M 29 d 46 u 63 /
95 13 N 30 e 47 v
96 14 O 31 f 48 w (pad) =
97 15 P 32 g 49 x
98 16 Q 33 h 50 y
99
100 Special processing is performed if fewer than 24 bits are available
101 at the end of the data being encoded. A full encoding quantum is
102 always completed at the end of a quantity. When fewer than 24 input
103 bits are available in an input group, zero bits are added (on the
104 right) to form an integral number of 6-bit groups. Padding at the
105 end of the data is performed using the '=' character.
106
107 Since all base64 input is an integral number of octets, only the
108 -------------------------------------------------
109 following cases can arise:
110
111 (1) the final quantum of encoding input is an integral
112 multiple of 24 bits; here, the final unit of encoded
113 output will be an integral multiple of 4 characters
114 with no "=" padding,
115 (2) the final quantum of encoding input is exactly 8 bits;
116 here, the final unit of encoded output will be two
117 characters followed by two "=" padding characters, or
118 (3) the final quantum of encoding input is exactly 16 bits;
119 here, the final unit of encoded output will be three
120 characters followed by one "=" padding character.
121 */
122
123 int
b64_ntop(unsigned char const * src,size_t srclength,char * target,size_t targsize)124 b64_ntop(unsigned char const *src, size_t srclength, char *target,
125 size_t targsize)
126 {
127 size_t datalength = 0;
128 unsigned char input[3];
129 unsigned char output[4];
130
131 while (2 < srclength) {
132 input[0] = *src++;
133 input[1] = *src++;
134 input[2] = *src++;
135 srclength -= 3;
136
137 output[0] = input[0] >> 2;
138 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
139 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
140 output[3] = input[2] & 0x3f;
141 assert(output[0] < 64);
142 assert(output[1] < 64);
143 assert(output[2] < 64);
144 assert(output[3] < 64);
145
146 if (datalength + 4 > targsize)
147 return (-1);
148 target[datalength++] = Base64[output[0]];
149 target[datalength++] = Base64[output[1]];
150 target[datalength++] = Base64[output[2]];
151 target[datalength++] = Base64[output[3]];
152 }
153
154 /* Now we worry about padding. */
155 if (0 != srclength) {
156 size_t i;
157 /* Get what's left. */
158 input[0] = input[1] = input[2] = '\0';
159 for (i = 0; i < srclength; i++)
160 input[i] = *src++;
161
162 output[0] = input[0] >> 2;
163 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
164 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
165 assert(output[0] < 64);
166 assert(output[1] < 64);
167 assert(output[2] < 64);
168
169 if (datalength + 4 > targsize)
170 return (-1);
171 target[datalength++] = Base64[output[0]];
172 target[datalength++] = Base64[output[1]];
173 if (srclength == 1)
174 target[datalength++] = Pad64;
175 else
176 target[datalength++] = Base64[output[2]];
177 target[datalength++] = Pad64;
178 }
179 if (datalength >= targsize)
180 return (-1);
181 target[datalength] = '\0'; /* Returned value doesn't count \0. */
182 return (datalength);
183 }
184
185 /* end */
186